The invention is directed to a drive arrangement for a motor vehicle and is concerned, in particular, with detecting the speeds of an internal combustion engine and the speeds of driving wheels of the motor vehicle.
In antilock braking systems (ABS) and drive slip regulating systems (ASR) of motor vehicles, the wheels must be detected very accurately. In conventional systems, speed sensors are arranged in the vicinity of the wheel bearings or special wheel bearings with integrated speed sensors are used. In either case, a comparatively high construction cost is required because the speed sensors must work under extreme operating conditions in the immediate area of the wheel. Similar considerations apply to conventional drive systems for accurate detection of the speed of the internal combustion engine, a knowledge of which is required for regulating and diagnosing the operation of the internal combustion engine.
In conventional drive arrangements for motor vehicles, the internal combustion engine drives the driving wheels via a mechanical transmission. It is known from the "VDI" Berichte No. 878, 191, pages 611 to 622, to couple a generator with the internal combustion engine of the motor vehicle in such a way that the generator is fixed with respect to rotation relative to the engine, while the driving wheels of the motor vehicle are connected with separate electric motors so as to be fixed with respect to rotation relative thereto, these electric motors being supplied with power by the generator arrangement via a d.c. voltage intermediate circuit. The generator arrangement and the electric motors of the known drive arrangement have a stator with a plurality of stator windings which are offset relative to one another in the circumferential direction and a rotor with a plurality of permanent magnets which are offset in the circumferential direction. The stator windings are connected to the d.c. voltage intermediate circuit via separate electronic commutator circuits associated with the generator arrangement and with the individual electric motors. To control the time sequence of currents in the individual stator windings, the commutator circuits generate pulse signals at timed intervals, which pulse signals trigger electronic switches, for example. Examples of such generators and electric motors are known from EP-A-0 159 005. Commutator circuits are described in EP-A-0 340 686.